Thru Hull Skin Fittings

Designed for underwater applications, the Arctic Steel Thru Hull Skin Fittings are cast in Duplex 2205 stainless steel, making them the material of choice when coming into permanent contact with seawater.


Uniquely cast in 2205 Stainless Steel, specifially for underwater applications. Also suitable for marine exhaust outlet.

Thru Hull Skin Fittings - Kemp Propulsion Systems (KPS)


1/2″ to 4″


BSP thread.
Mirror polished outside flange.


Long reach fittings available in 3/4″, 1″, 1.1/2″
Standard sizes from 1/2″ to 4″
Suitable for high temperature applications (up to 60C)


3.1 Certificate available on request

Duplex 2205 Stainless Steel

Australian Stainless Steel Development Association recommends the following general rules:

  • 304 may be used for fully exposed components, frequently washed with fresh water
  • 316 may be used for all hull and deck fitting applications above the water line
  • 2205 offers higher strength and therefore lighter weight components for the same application and 316 and can additionally be upsed up to 60 degrees celcuius for wet exhaust system and fully submersed applications.

Duplex stainless steels consist of a microstructure of approximately 50% austenite and 50% ferrite grains – the most common is 2205.

The following properties of 2205 make it a better choice of stainless steel for Thru Hull fittings:

  • Yield strength, twice that of 304 or 316 – offering added security for critical hull penetration fittings
  • Much higher resistance to pitting and crevice corrosion in seawater than 316 (see PREN table to the right)
  • Twice the fatigue and corrosion strength of 316.


Thru Hull Skin Fitting - Duplex Infographic